The proposed studies are aimed at defining the precise role of products coded for by genes associited with the major murine histocompatibility complex (H-2) in immunity to syngeneic tumors. The experimental model for these studies will consist of methyl-cholanthrene-induced fibrosarcomas derived in congenic, congenic-recombinant and congenic-mutant inbred strains of mice as well as in F1 hybrids appropriate for analysis of the role of H-2 subloci in tumor-specific immunity. These tumors have previously been characterized with respect to in vivo growth, lethality, immunogenicity and alloantigenicity in syngeneic and congenic strains; moreover, the relative alloantigen content of many of these tumors has been determined by serological and cellular assays. Analysis of the immune response to syngeneic tumors will include further resolution of the specificity of hyperimmune effector peritoneal exudate cells (HYPEC) from syngeneic hosts. Systematic probation of HYPEC will be performed in order to exclude or include possible participation of respectively, non-T or T-lymphocytes, in the in vitro tumor-specific cytolytic response. Antisera from tumor-hyperimmunized syngeneic and congenic hosts will be tested for anti-TSTA directed serological activity (i.e., cytotoxic antibody, blocking antibody, antibody-dependent cell-mediated cytotoxic antibody). Assessment of the TSTA-H-2 intramembrane relationship on methylcholanthrene tumors will be accomplished using the short-term in vitro HYPEC-mediated cytotoxicity test alone and in conjunction with tumor-specific and H-2 directed antisera.